I85PREP
⌘ K
MN CDL General Knowledge study materials
MN CDL General Knowledge study resources

MN CDL General Knowledge practice questions

One question at a time. Build your MN CDL General Knowledge understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Vehicle Inspection and Basic Control

Before starting a trip in a commercial vehicle, the pre-trip inspection is required primarily to confirm that:

  1. the trip log has been signed by a dispatcher
  2. the fuel tank is filled to capacity for the planned route
  3. the cargo has already been weighed at a certified scale
  4. the vehicle's safety equipment and critical components are in proper working order Correct answer.

Explanation

The pre-trip inspection is a safety check that the driver performs to confirm that brakes, tires, lights, steering, and other critical parts are functioning before operating the vehicle. It is not a fuel, cargo-weighing, or paperwork task, although those may happen at other points in the trip.

Question 2Vehicle Inspection and Basic Control

When checking slack adjusters during a pre-trip inspection on a vehicle with air brakes, the push rod travel should be:

  1. measured only when the engine is off and the system is empty
  2. as long as the rod can physically extend
  3. ignored if the brake pedal feels firm
  4. within the limit specified for that chamber type Correct answer.

Explanation

Excessive push rod travel means the brakes are out of adjustment and may not apply fully. Each brake chamber type has a specified maximum stroke, and the driver compares the measured travel against that limit. A firm pedal alone does not prove the slack adjusters are correctly set.

Question 3Vehicle Inspection and Basic Control

During a pre-trip inspection you find a small puddle of oil under the engine. What is the correct action?

  1. Add oil until the level reads full and continue the trip
  2. Wipe it up and depart because small drips are normal on older engines
  3. Cover the puddle with cardboard so it is not visible at the next stop
  4. Note it, identify the source, and have it repaired before dispatch if it indicates a leak Correct answer.

Explanation

Any fluid leak can signal a mechanical problem that may worsen on the road, and leaking oil is also a safety and environmental hazard. The driver should identify the source and, if it is a genuine leak, ensure it is repaired before operating. Hiding or topping off the fluid does not fix the underlying fault.

Question 4Vehicle Inspection and Basic Control

When performing the walkaround inspection, which of these belongs in the check of the vehicle's lights?

  1. Checking that the radio antenna is fully extended
  2. Verifying that the wiper blades are the correct brand
  3. Confirming that clearance, marker, brake, and turn signals all illuminate Correct answer.
  4. Confirming that the fuel cap is painted the same color as the cab

Explanation

The lighting check covers all required lamps, including clearance lights, marker lights, brake lights, and turn signals, so the driver knows they function before driving. Antenna, wiper brand, and paint color are unrelated to whether the required lighting works.

Question 5Vehicle Inspection and Basic Control

How much tread depth must remain in every major groove of a front steering tire on a commercial vehicle?

  1. At least 1/32 of an inch
  2. At least 6/32 of an inch
  3. At least 4/32 of an inch Correct answer.
  4. At least 2/32 of an inch

Explanation

Federal rules require at least 4/32 inch of tread in every major groove of a front steering tire and at least 2/32 inch on all other tires. Steering tires carry the highest demand for grip, so they have the stricter limit.

Question 6Vehicle Inspection and Basic Control

A tire has a visible bulge in the sidewall. What should the driver do?

  1. Rotate the tire to a trailer position and continue
  2. Inflate the tire to the maximum sidewall pressure to remove the bulge
  3. Remove the tire from service before operating the vehicle Correct answer.
  4. Reduce speed and use the tire only on short trips

Explanation

A sidewall bulge indicates internal cord damage, and the tire can fail suddenly at highway speed. Such a tire must be taken out of service rather than nursed along or moved to another position. Overinflation will not repair structural damage and risks a blowout.

Question 7Vehicle Inspection and Basic Control

When checking the engine compartment during the pre-trip inspection, the coolant level should be:

  1. verified by the color of the coolant alone
  2. filled to the very top of the radiator neck
  3. at the level marked on the reservoir or radiator when the engine is cool Correct answer.
  4. checked only after the engine has run at operating temperature

Explanation

Coolant is checked with the engine cool, both to get an accurate reading and to avoid serious burns from pressurized hot coolant. The level should match the marked full line, not be overfilled or judged by color.

Question 8Vehicle Inspection and Basic Control

Before backing a tractor-trailer, the driver should first:

  1. turn on the radio to stay alert
  2. get out and check the area behind the vehicle for obstructions Correct answer.
  3. raise the engine rpm to keep the trailer moving
  4. release the parking brake and let the vehicle roll

Explanation

Blind spots behind a large vehicle can hide people, vehicles, and objects, so the driver must walk around and check the path before backing. Releasing the brake to roll before checking the area removes control and can cause a collision.

Question 9Vehicle Inspection and Basic Control

When backing a trailer, you want the rear of the trailer to move to the left. Which action produces that result?

  1. Applying the trailer hand valve
  2. Turning the steering wheel to the right Correct answer.
  3. Turning the steering wheel to the left
  4. Accelerating sharply while holding the wheel straight

Explanation

When backing, turning the steering wheel right causes the tractor's rear to swing left, which pushes the trailer's rear to the left. Steering the opposite way moves the trailer's rear to the right. Speed and the hand valve do not determine the direction of trailer travel.

Question 10Vehicle Inspection and Basic Control

When making a right turn in a large commercial vehicle, the safe technique is to:

  1. brake hard in the middle of the turn to slow the trailer
  2. stay tight to the right curb and accelerate through the turn
  3. turn from the left lane without signaling
  4. swing wide to the left before the turn and watch the right rear wheels Correct answer.

Explanation

Large vehicles need extra room, so the driver moves left before a right turn to keep the rear wheels from striking the curb or a pedestrian. The driver must also check the right side mirror through the turn. Staying tight to the curb risks the rear wheels off-tracking onto the curb or a person.

Question 11Vehicle Inspection and Basic Control

Off-tracking when turning a long combination vehicle means that:

  1. the steering axle turns more sharply than the drive axles
  2. the trailer brakes apply later than the tractor brakes
  3. the rear wheels follow a shorter path than the front wheels Correct answer.
  4. the vehicle's speed increases through the turn

Explanation

Off-tracking is the tendency of the rear axles to cut inside the path traced by the front wheels, and the effect grows with vehicle length. Drivers must allow for this by leaving room on the inside of turns. It is a geometry effect, not a braking or speed issue.

Question 12Vehicle Inspection and Basic Control

When driving a commercial vehicle at highway speed, the following distance should generally be:

  1. at least one second for each ten feet of vehicle length Correct answer.
  2. a fixed two seconds regardless of vehicle length
  3. one car length for every ten miles per hour
  4. as close as the vehicle ahead allows without braking

Explanation

A common rule is to allow at least one second of following distance for each ten feet of vehicle length, measured at speeds under 40 mph, and to add a second at higher speeds. Heavier, longer vehicles need more stopping distance than the fixed two-second car rule.

Question 13Vehicle Inspection and Basic Control

The most important reason to look well ahead while driving a commercial vehicle is to:

  1. keep the engine at a steady temperature
  2. keep the vehicle centered in the lane
  3. reduce the need to use the mirrors
  4. spot hazards early enough to plan a safe response Correct answer.

Explanation

Scanning far ahead gives the driver time to identify problems such as stopped traffic, intersections, or debris and to adjust speed or lane position smoothly. A loaded vehicle cannot stop or change direction quickly, so early detection is the main defense.

Question 14Vehicle Inspection and Basic Control

You are driving downhill on a long, steep grade with a heavy load. The correct braking technique is to:

  1. coast in neutral to save fuel and rely on the service brakes
  2. shift to a higher gear to keep the engine from revving
  3. hold the brake pedal down continuously the whole way down
  4. select a lower gear before the grade and use engine braking with controlled brake application Correct answer.

Explanation

Selecting a low gear before descending lets engine braking help control speed, and short, firm brake applications keep the brakes from overheating. Coasting in neutral or riding the brakes builds heat and can cause brake fade or loss of control.

Question 15Vehicle Inspection and Basic Control

On a wet road, the danger of hydroplaning increases when:

  1. the wipers are on high speed
  2. the vehicle is lightly loaded
  3. the road has a slight crown
  4. speed increases and tire tread is worn Correct answer.

Explanation

Hydroplaning occurs when water builds up faster than the tread can channel it away, and higher speed plus shallow tread both make that more likely. Reducing speed and keeping good tread depth are the primary defenses. Load, wiper setting, and road crown are not the main factors.

Question 16Vehicle Inspection and Basic Control

When driving in fog, you should:

  1. slow down and use low-beam headlights Correct answer.
  2. turn on the hazard flashers and maintain highway speed
  3. follow the tail lights of the vehicle ahead closely
  4. use high-beam headlights to see farther

Explanation

Low beams aim down and reduce glare reflected back by fog, while slowing down gives more time to react to hazards hidden by reduced visibility. High beams reflect off the fog, and tailgating removes the stopping margin you need.

Question 17Vehicle Inspection and Basic Control

If your vehicle begins to skid on an icy road, the first thing to do is:

  1. apply the brakes as hard as possible
  2. accelerate to pull out of the skid
  3. turn the steering wheel sharply in the opposite direction
  4. stop braking and steer in the direction you want the front of the vehicle to go Correct answer.

Explanation

Releasing the brakes lets the tires regain grip, and steering where you want the vehicle to go helps the front tires realign with the direction of travel. Hard braking or sharp counter-steering can worsen the skid.

Question 18Vehicle Inspection and Basic Control

When a tire blows out at highway speed, you should:

  1. steer sharply toward the shoulder to get off the road fast
  2. brake hard immediately to stop as quickly as possible
  3. accelerate briefly to stabilize the vehicle
  4. hold the steering wheel firmly and slow gradually before pulling off the road Correct answer.

Explanation

A firm grip keeps the vehicle from veering while you ease off the accelerator and let speed drop before moving to the shoulder. Hard braking or sharp steering after a blowout can cause a loss of control or a rollover.

Question 19Vehicle Inspection and Basic Control

Before driving through a low underpass, a driver of a tall vehicle should:

  1. assume the posted clearance is approximate and proceed
  2. lower the tire pressure to reduce overall height
  3. speed up to pass under before traffic arrives
  4. know the vehicle's height and compare it with the posted clearance Correct answer.

Explanation

Posted clearance signs give the maximum safe height, and the driver must know the actual height of the loaded vehicle, including any cargo or equipment, before proceeding. Assuming the sign is approximate or trying to rush through risks a bridge strike.

Question 20Vehicle Inspection and Basic Control

When a commercial vehicle is parked on a grade, the wheels should be:

  1. turned into the curb or toward the edge so the vehicle rolls away from traffic if it moves Correct answer.
  2. turned away from the curb on any downhill grade
  3. left perfectly straight regardless of the slope
  4. blocked only by setting the parking brake

Explanation

Turning the front wheels so the vehicle would roll into the curb or off the road, rather than into traffic, provides a backup if the parking brake fails. The parking brake should also be set, but wheel direction adds a second layer of protection.

Question 21Vehicle Inspection and Basic Control

Which of these is a sign that a driver may be too fatigued to continue safely?

  1. Comfortable cabin temperature
  2. Steady steering and consistent speed
  3. Frequent yawning and difficulty keeping the eyes focused Correct answer.
  4. Feeling alert after a short break

Explanation

Yawning, heavy eyelids, and trouble focusing are warning signs that fatigue is impairing alertness, and continuing to drive risks a fall-asleep crash. The safe response is to stop and rest, not to push on. Alertness after a break and steady driving suggest the opposite condition.

Question 22Vehicle Inspection and Basic Control

When confronted with an aggressive driver, the safest response is to:

  1. avoid eye contact and give the other driver plenty of space Correct answer.
  2. return the gesture to show you are not intimidated
  3. brake suddenly to make the other driver back off
  4. speed up to stay ahead of the other vehicle

Explanation

Avoiding eye contact and increasing following distance keeps a confrontation from escalating and gives you room to maneuver if the other driver acts unpredictably. Racing or retaliating raises the risk of a crash.

Question 23Vehicle Inspection and Basic Control

A commercial vehicle's mirrors should be adjusted so that:

  1. they show only the trailer's front corner
  2. the driver can see the sides and rear of the vehicle with minimal blind area Correct answer.
  3. the driver can see mostly the sky and the cab interior
  4. they are folded in whenever the vehicle is moving

Explanation

Properly adjusted mirrors show the sides of the vehicle and the traffic lane behind, reducing the blind spots where a passing vehicle could hide. Mirrors aimed at the sky or folded in defeat their purpose.

Question 24Vehicle Inspection and Basic Control

When checking the coupling of a tractor to a semitrailer, the driver should confirm that:

  1. the fifth wheel is greased but not latched
  2. the trailer is resting on the landing gear
  3. the locking jaws are closed around the kingpin and a pull test holds Correct answer.
  4. the air lines are disconnected

Explanation

A secure coupling requires the fifth wheel jaws to close fully around the kingpin, and a gentle pull test confirms the trailer will not separate. Leaving the trailer on its landing gear or with lines disconnected is not a completed coupling.

Question 25Vehicle Inspection and Basic Control

During an en route inspection after several hours of driving, the driver should pay particular attention to:

  1. tires, brakes, lights, and the security of the cargo Correct answer.
  2. the radio station presets
  3. the number of miles remaining on the fuel gauge
  4. the color of the cab's interior trim

Explanation

An en route inspection checks the items most likely to change during a trip, such as tire condition and pressure, brake adjustment, lamp function, and cargo securement. Interior trim, fuel range, and radio settings are not safety inspection items.

Question 26Vehicle Inspection and Basic Control

During a pre-trip inspection, you check the slack adjusters on a vehicle with air brakes. A properly functioning automatic slack adjuster should show a pushrod travel that is within the limit and a brake chamber stroke that is consistent across the axle. If one slack adjuster looks noticeably different from the others on the same axle, what does this most likely indicate?

  1. A brake adjustment or mechanical problem on that wheel that requires repair before driving Correct answer.
  2. A harmless difference that can be ignored until the next scheduled service
  3. An indication that the brake lining on that wheel is still new and seated
  4. A normal condition caused by the brake chamber being slightly larger on that side

Explanation

Automatic slack adjusters should keep pushrod travel within the legal limit and roughly equal on wheels of the same axle. A pushrod that is out of adjustment or travels more than the others signals a brake defect, such as a slipping adjuster or worn components, that must be corrected before the vehicle is driven.

Question 27Vehicle Inspection and Basic Control

When you perform the pre-trip inspection, the correct order of checking the engine compartment is to:

  1. check only the fluid levels, since belts and hoses are inspected during service
  2. start at one corner and work systematically around the compartment so nothing is missed Correct answer.
  3. start the engine first, then inspect belts and hoses while they are moving
  4. open the hood and look quickly at the major components before starting the engine

Explanation

A systematic pattern around the engine compartment ensures that every component, such as belts, hoses, fluid levels, and the steering and suspension parts you can see, gets checked. Inspecting in a set order prevents skipping items.

Question 28Vehicle Inspection and Basic Control

You are about to start a tractor-trailer and the engine will not crank. Before assuming a mechanical failure, which check is most appropriate?

  1. Pump the accelerator several times and try again
  2. Check the air pressure gauge to see whether the tanks are full
  3. Release the parking brake and roll the vehicle slightly
  4. Confirm the transmission is in neutral and the clutch is depressed if the vehicle has a manual transmission Correct answer.

Explanation

Many heavy vehicles have a neutral safety or clutch interlock that prevents cranking unless the transmission is in neutral and, on manuals, the clutch is pushed in. Confirming these conditions rules out an operator error before you suspect a starter or battery problem.

Question 29Vehicle Inspection and Basic Control

When you are seated in the driver's position before moving, the steering wheel should be held:

  1. with both hands close together at the bottom of the wheel
  2. with one hand at the top of the wheel for the best leverage
  3. loosely with the palms open, letting the wheel self-center
  4. with both hands on opposite sides of the wheel, so you can turn fully in either direction Correct answer.

Explanation

Holding the wheel with both hands on opposite sides gives you the greatest control and lets you turn sharply in either direction without repositioning. It also keeps your arms clear of the wheel's path if it kicks back.

Question 30Vehicle Inspection and Basic Control

You are about to move a loaded combination vehicle from a stop on a level road. Which action best reduces the risk of a rollover or loss of control during the first few seconds of acceleration?

  1. Check that the trailer brakes release smoothly and accelerate gradually while monitoring mirrors and gauges Correct answer.
  2. Release the clutch abruptly to confirm the driveline is engaged
  3. Keep the steering wheel turned toward the curb until the trailer is fully straight
  4. Accelerate firmly to get up to speed quickly and clear the intersection

Explanation

Smooth, gradual acceleration after confirming the trailer brakes have released keeps the combination stable and lets you watch for traffic and check that nothing is dragging. Hard acceleration or abrupt clutch release can upset the load and driveline.

Question 31Shifting, Backing, and Turning

Before making a right turn at an intersection in a large commercial vehicle, what should you do with your vehicle's position?

  1. Swing wide to the left before starting the turn
  2. Stop in the crosswalk to check for pedestrians
  3. Stay in the right lane and keep the rear wheels close to the curb Correct answer.
  4. Move into the left lane to give the trailer room

Explanation

A right turn in a large vehicle must be set up from the right lane, with the rear wheels tracking close to the curb. Swinging left invites vehicles to pass on your right, which is the space the trailer will sweep into. Keeping the turn tight protects the right-side space you cannot see well.

Question 32Shifting, Backing, and Turning

Which statement best describes off-tracking when a tractor-trailer makes a turn?

  1. The trailer wheels follow exactly the same path as the tractor's front wheels
  2. The front wheels always track outside the lane line on a curve
  3. The front wheels follow a wider path than the rear wheels
  4. The trailer wheels follow a path inside the path of the tractor's front wheels Correct answer.

Explanation

Off-tracking means the rear wheels of a long vehicle track inside the path of the front wheels during a turn. The longer the wheelbase and trailer, the greater the amount of off-tracking. Drivers must allow room for the rear of the vehicle to cut the corner.

Question 33Shifting, Backing, and Turning

When backing a tractor-trailer, which method is recommended to keep the trailer tracking straight?

  1. Back at a steady fast speed to reduce correction
  2. Rely only on the mirrors and avoid turning your head
  3. Steer with the top of the steering wheel in the direction you want the trailer to go Correct answer.
  4. Turn the wheel opposite the trailer direction and hold it there

Explanation

When backing, you steer the trailer by turning the wheel toward the direction you want the rear of the trailer to travel. Watching the trailer in the mirrors and using small corrections keeps it tracking. Fast backing and fixed steering make the trailer drift and jackknife.

Question 34Shifting, Backing, and Turning

What is the safest way to handle a backing maneuver you cannot complete with good visibility?

  1. Back quickly to spend less time in a blind spot
  2. Back slowly and trust the mirrors
  3. Use a helper to guide you and stop when you lose sight of them Correct answer.
  4. Sound the horn and back without checking

Explanation

When visibility behind the vehicle is inadequate, use a helper as a spotter and stop immediately if you lose sight of them. The spotter should stand where you can see them and where they can see the path behind. Never continue backing blind.

Question 35Shifting, Backing, and Turning

When turning left in a large vehicle, where should you begin the turn from?

  1. From the right lane to widen the arc
  2. From the lane closest to the center line or turn lane Correct answer.
  3. From any lane as long as you signal
  4. From the shoulder to give the trailer room

Explanation

A left turn should be started from the lane closest to the center line or from a designated left-turn lane. Starting from the right lane can cause a crash with traffic passing on your left. The rear wheels will still cut inside, so watch the trailer's path.

Question 36Shifting, Backing, and Turning

Why should you check both mirrors and a blind spot before changing lanes in a commercial vehicle?

  1. Blind-spot checks are required only when towing a trailer
  2. Mirrors on a large vehicle cover every angle behind the trailer
  3. Large vehicles have blind spots that mirrors do not fully cover Correct answer.
  4. The mirrors only show the area directly beside the cab

Explanation

Even with properly adjusted mirrors, large vehicles have blind spots along both sides and directly behind. A head check or mirror scan plus signal and speed adjustment reduces the risk of sideswiping a vehicle hidden in those areas. Never rely on mirrors alone.

Question 37Shifting, Backing, and Turning

You are driving a 53-foot trailer and must turn right at a corner with a stop sign and a raised curb. What is the best plan?

  1. Set up in the right lane, pull forward past the stop line, and turn wide enough for the trailer to clear the curb Correct answer.
  2. Turn from the left lane and let the trailer cut across the curb
  3. Back up after the turn to reposition the trailer
  4. Stop at the line and turn sharply to keep the trailer inside the lane

Explanation

On a tight right turn, the driver should set up in the right lane and may need to swing slightly left after clearing the stop line so the trailer does not climb the curb. The maneuver must still keep other traffic from passing on the right. Reversing at an intersection is unsafe and often illegal.

Question 38Shifting, Backing, and Turning

While backing a trailer into a loading dock on the right side, the trailer begins to drift left. What should you do?

  1. Turn the steering wheel toward the left to bring the trailer back
  2. Stop and unhook the trailer
  3. Turn the steering wheel toward the right to bring the trailer back Correct answer.
  4. Accelerate to straighten the trailer quickly

Explanation

When backing, the trailer moves in the direction you turn the wheel. If the trailer drifts left, steer right to bring the rear of the trailer back toward the dock. Make small corrections early rather than large ones late.

Question 39Shifting, Backing, and Turning

A driver must make a right turn where a bicyclist is riding in the bike lane on the right. What is the correct action?

  1. Sound the horn and turn immediately
  2. Merge into or block the bike lane early so the bicyclist cannot pass on the right, then turn when clear Correct answer.
  3. Turn across the bicyclist because the truck has the right of way
  4. Speed up to complete the turn before the bicyclist arrives

Explanation

A right-turning large vehicle should close the gap on its right so no one can move into the space the trailer will sweep through. Signal early, position right, and wait until the bicyclist is clear before turning. The truck does not automatically have the right of way over the bicyclist.

Question 40Shifting, Backing, and Turning

You are backing a straight truck with no trailer. How should you use your mirrors?

  1. Watch only the left mirror because it is closest to the driver
  2. Adjust the mirrors to show only the ground behind the bumper
  3. Check both mirrors frequently and also look directly through the rear window if one is available Correct answer.
  4. Fold the mirrors in to avoid hitting anything

Explanation

When backing a straight truck, use both mirrors and, if the vehicle has a rear window, look directly through it as well. Checking both sides keeps you aware of obstacles and pedestrians. Mirrors should be adjusted before the maneuver, not folded in.

Question 41Shifting, Backing, and Turning

A tractor-trailer is making a wide right turn at a corner where a pedestrian is waiting at the curb on the right. Why is this situation especially dangerous?

  1. The front bumper swings outward toward the pedestrian
  2. The pedestrian is required to yield to all turning trucks
  3. The trailer's rear wheels cut inside and can strike the pedestrian on the corner Correct answer.
  4. The mirrors block the driver's view of the crosswalk

Explanation

Because of off-tracking, the rear wheels of a turning trailer track inside the front wheels and can ride over the curb or corner where a pedestrian is standing. Drivers must check the right side and the crosswalk before and during the turn. Pedestrians in a crosswalk generally have the right of way.

Question 42Shifting, Backing, and Turning

What is the recommended maximum speed for backing a large commercial vehicle?

  1. The same speed used for normal forward driving
  2. About 15 mph to clear the area quickly
  3. A brisk walking pace or slower, using a spotter when needed Correct answer.
  4. Whatever speed keeps the engine from stalling

Explanation

Backing should be done at a walking pace or slower so there is time to stop for pedestrians, vehicles, or obstacles. A spotter should be used whenever visibility is limited. Faster backing shortens reaction time and increases damage in a collision.

Question 43Shifting, Backing, and Turning

Before changing lanes on a multi-lane highway in a tractor-trailer, what sequence of actions is most appropriate?

  1. Check the blind spot, signal, and move immediately
  2. Honk, then change lanes without checking mirrors
  3. Signal, check mirrors, check the blind spot, then move gradually when clear Correct answer.
  4. Signal and change lanes at once to avoid losing the gap

Explanation

The correct sequence is to signal your intention, check both mirrors, verify the blind spot with a head check, and then move gradually when the lane is clear. Large vehicles need more time and space to change lanes, so the maneuver should be smooth and predictable.

Question 44Shifting, Backing, and Turning

A driver in a long combination vehicle approaches a left turn onto a narrow two-way street. What should the driver anticipate about the trailer?

  1. The trailer will swing outward only if the turn is made below 10 mph
  2. The trailer's rear wheels will cut inside the turn and may strike the near curb or a pole Correct answer.
  3. The trailer will follow the tractor exactly with no offset
  4. The trailer will track outside the path of the tractor and may strike the far curb

Explanation

In any turn, the rear wheels of the trailer cut inside the path of the tractor's front wheels. On a narrow street this means the trailer can strike the near curb, a sign, or a parked vehicle. The driver must allow for that inside sweep when judging the turn.

Question 45Shifting, Backing, and Turning

When is it acceptable to back a commercial vehicle on a highway shoulder or in an intersection?

  1. Whenever you miss your exit and need to return
  2. Only when it is safe and legal, which generally excludes highway shoulders and intersections Correct answer.
  3. Whenever a spotter is available
  4. Only during daylight hours

Explanation

Backing is permitted only when it can be done safely and legally. Highway shoulders and intersections are generally not legal or safe places to back because of traffic and limited visibility. Missing an exit should be handled by continuing to the next one.

Question 46Shifting, Backing, and Turning

A driver must turn a tractor-trailer right from a narrow street onto a wider street. Which setup gives the best result?

  1. Approach in the left lane and swing right during the turn
  2. Approach in the right lane, keep the turn tight at the start, and allow the trailer to clear the corner Correct answer.
  3. Approach in the center of the road and turn sharply
  4. Approach in the right lane and accelerate through the turn

Explanation

The safest setup is to approach in the right lane, begin the turn without swinging left into other traffic, and allow enough room for the trailer to clear the corner. The driver must watch the right mirror to confirm the trailer clears the curb. Accelerating through the turn reduces control.

Question 47Shifting, Backing, and Turning

A driver is backing a tractor-trailer around a corner into an alley. The trailer is 53 feet long and the alley is narrow. What is the most important factor for success?

  1. Setting up the tractor at the correct angle and making small steering corrections Correct answer.
  2. Using only the left mirror to judge the trailer
  3. Keeping the steering wheel straight throughout the maneuver
  4. Backing quickly so traffic is not delayed

Explanation

Backing a long trailer into a narrow alley depends on the initial setup angle of the tractor and on small, early steering corrections. A poor setup angle forces large corrections that can jackknife the combination. Speed and one-mirror viewing increase the risk of a collision.

Question 48Shifting, Backing, and Turning

A tractor-trailer with a 53-foot trailer is turning right at a corner where the curb radius is small and a utility pole stands close to the corner. What is the best way to judge clearance?

  1. Rely on the front bumper clearing the pole and turn without further checks
  2. Turn sharply to keep the trailer as far from the pole as possible
  3. Watch the right mirror and the trailer's rear wheels as they approach the pole, adjusting the turn before they reach it Correct answer.
  4. Back up if the trailer gets close to the pole

Explanation

Clearance at a tight corner is judged by watching the trailer's rear wheels in the right mirror as they approach the pole, and adjusting the turn before they reach it. The front bumper clearing the pole says nothing about the trailer's path. Backing at the corner is unsafe and often illegal.

Question 49Shifting, Backing, and Turning

A driver must make a right turn in a large truck where the right lane is occupied by a stopped bus. What is the safest course of action?

  1. Turn from the left lane across the bus's path
  2. Squeeze between the bus and the curb to keep the turn tight
  3. Sound the horn until the bus moves out of the lane
  4. Wait behind the bus or change lanes legally once it moves, then set up the turn from the proper right position Correct answer.

Explanation

A right turn must be made from the right lane, so if that lane is blocked, the driver should wait or reposition legally once it is clear. Turning from the left lane across the bus creates a serious conflict. Squeezing between the bus and the curb leaves no room for the trailer's sweep.

Question 50Shifting, Backing, and Turning

A driver is backing a tractor-trailer into a dock on the left side and the trailer begins to jackknife. What is the best recovery action?

  1. Apply the trailer brakes only and keep the wheel turned
  2. Pull forward to straighten the combination, then resume backing with smaller corrections Correct answer.
  3. Continue backing and steer harder to force the trailer straight
  4. Accelerate to push the trailer through the jackknife

Explanation

When a trailer starts to jackknife while backing, the safest recovery is to pull forward to straighten the combination and then resume with smaller, earlier corrections. Forcing the wheel or accelerating worsens the angle. Pulling forward restores control before the angle becomes unrecoverable.